#include <iostream>
#include <cmath>
#include <stack>
#include <iomanip>
#include <limits>
#include <queue>
#include <map>
#include <set>
#include <algorithm>
#include <deque>
#include <atcoder/all>
#include <unordered_set>
using namespace atcoder;
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define Yes cout << "Yes" << endl
#define No cout << "No" << endl
#define vl vector<long long>
#define vvl vector<vector<long long>>
#define vvvl vector<vector<vector<long long>>>
#define vc vector<char>
#define vvc vector<vector<char>>
#define vb vector<bool>
#define vvb vector<vector<bool>>
#define nall(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define chmax(x, y) x = max(x, y)
#define chmin(x, y) x = min(x, y)
#define yu_qgrid(x, y) ((x) * (x) + (y) * (y)) // ユークリッド距離 (sqrtはしない)
#define mannhattan(x1, x2, y1, y2) abs(x1 - x2) + abs(y1 - y2)
#define PI 3.14159265359
using ll = long long;
//using mint = modint1000000007;
using mint = modint998244353;
using P = pair<ll, ll>;

vl di = {1, 0, -1, 0}; // 下、左、上、右
vl dj = {0, -1, 0, 1};


bool out_grid(ll i, ll j, ll h, ll w) { return !(0 <= i && i < h && 0 <= j && j < w); }

ll INF = 1e18;
int main(){
    ll n,m;
    cin >> n >> m;
    string s;
    cin >> s;
    vvl g(n);
    rep(i,m){
        ll a,b;
        cin >> a  >> b;
        a--;b--;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    ll count_hatena = 0;
    rep(i,n){
        if(s[i] == '?') count_hatena++;
    }
    mint ans = 0;
    map<char,char> mp;
    mp['a'] = 'o';
    mp['o'] = 'i';

    auto dfs = [&](auto dfs,char pre,ll hatena,ll v,vb seen) -> void{
        char nex = mp[pre];
        for(ll u : g[v]){
            if(seen[u])continue;
            if(pre == 'o'){
                ll e = INF;
                if(s[u] == nex){
                    e = count_hatena-hatena;
                }
                if(s[u] == '?'){
                    e = count_hatena-hatena-1;
                }
                if(e == INF)continue;
                if(e == 0){
                    ans += 1;
                }
                else{
                    mint base = 26;
                    base.pow(e);
                    ans += base;
                }
            }
            else{
                seen[u] = true;
                if(s[u] == '?'){
                    dfs(dfs,nex,hatena+1,u,seen);
                }
                if(s[u] == nex){
                    dfs(dfs,nex,hatena,u,seen);
                }
                seen[u] = false;
            }
        }
        return;
    };
    for(int v = 0;v < n;v++){
        vb seen(n);
        seen[v] = true;
        if(s[v] != 'a' && s[v] != '?')continue;
        if(s[v] == 'a'){
            dfs(dfs,'a',0,v,seen);
        }
        else{
            dfs(dfs,'a',1,v,seen);
        }
    }
    cout << ans.val() << endl;
     
}